Process for improving hydrocarbon oils boiling in the gasoline range



.resort to a more costly catalytic reforming process.

United States Patent PROCESS FOR INIPROVING HYDROCARBON OILS BOILING INTHE GASOLINE RANGE George Cornelis Adriaan Schuit and Marius t Hart,

Amsterdam, Netherlands, assignors to Shell Development Company,Emeryville, Calif., a corporation of Delaware No Drawing. ApplicationJune 2, 1952, Serial No. 291,324

Claims priority, application Netherlands June 13, 1951 4 Claims. (Cl.196-60) This invention relates to a process for improving hyrocarbonoils of the gasoline boiling range by improving their knock stability,i. e., improving their anti-knock qualities. The invention relates tothe improvement of the knock stability of gasolines and naphthas,particularly those which have been obtained directly from petroleum (i.e., straight-run gasoline and naphtha) and particularly those which havea relatively high content of naphthenic hydrocarbons. Although theprocess is particularly adapted for the treatment of straight-runnaphthas .of high naphthene content, it is also applicable for thetreatment of other naphthenic hydrocarbon fractions of similarcharacter.

The tendency for a gasoline to knock when used in an internal combustionengine is usually indicated by the octane number. In the following theknocking tendency will be expressed by the Motor Method octance numberwhich is otherwise designated the ONF-Z number.

Gasolines obtained from petroleum by distillation, i. e., straight-rungasolines, and also certain cracked and synthetic gasolines, have pooranti-knock characteristics. It is well known that such gasolines can bematerially upgraded by suitable thermal or catalytic treatment; suchtreatments to upgrade the gasoline are generally referred to asreforming treatments. 1

In any reforming treatment there is an appreciable loss .of gasoline andin every case this loss increases sharply as the extent of upgrading isincreased by the application of increasingly severe treating conditions.This loss is most important and limits the extent of upgrading which maybe economically applied in any given case.

It is possible by thermal'methods to upgrade the usual run of gasolinesup to a certain point without excessive .loss, and since thermalreforming is the least costly type of reforming process, such thermalreforming is preferred :in all cases where the degree of upgrading issufficient :to meet the demands. Any attempt to upgrade the gasolinefurther by thermal reforming results in little improvement in octanenumber and prohibitively high losses.

During the past'years the anti-knock requirements of gasoline havegenerally increased to the extent that the upgrading obtainable bythermal reforming is often not sufficient. It is, therefore, nowbecoming necessary to In catalytic reforming, as-in thermal reforming,the yield decreases as the upgrading is increased. Catalytic reforminghas the advantage over thermal reforming, however, in that at a givenloss the octane number can be increased to a somewhat higher value. Itis therefore possible to attain higher octane numbers in the importantregion of 80 F2 and above. Various catalytic reforming processes'havebeen proposed and, neglecting processing costs for the moment, thesedifferent only in the yield octane number relationships obtainable inthe critical high octane number region. An improvement of even oneoctane number at a given yield, or an improvement of 2 even 1% increasedyield at a given octane number represents a very valuable and importantimprovement. This is particularly the case in the high-octane regionabove 30 15-2 since one octane number improvement in this region isworth several octane numbers in the lower regions.

The known and hitherto suggested catalytic reforming treatmentsgenerally involve treating the gasoline or naphtha in the vapor phasewith a catalyst such as molybdenum oxide, chromium oxide, tungstensulfide, nickel sulfide, or the like. These and other related catalystsare generally applied with inert carrier or support materials such asalumina, silica, pumice, and the like which provide an extended surface.When reforming gasolines with such catalysts a certain amount ofdehydrogenation takes place and the gasoline is, among other things,made more aromatic in nature. It is recognized, however, that reformingis not a simple aromatization process and that the aromaticity (anilinepoint) of the product is not a proper criterion of the reformingefiiciency. The loss of gasoline caused by the reforming treatment isdue in part to a somewhat increased density of the reformed product, butis mainly due to conversion of a substantial part of the gasoline feedto gases, higher boiling products, and tar or coke. These losses aregenerally believed to be largely the result, directly or indirectly, ofdealkylation, cracking, and condensation reactions. I

While the mentioned catalytic reforming treatments are capable ofupgrading all low octane gasolines they are much more efiicient in thetreatment of some gasolines than others. Those gasolines in which theproportion of carbon atoms found in polymethylene rings is large aregenerally most amenable to such treatment. However, those gasolines highin naphthenic hydrocarbon content have, on the other hand, in manycases, been most difiicult to upgrade without large losses. This is duelargely to the fact that the naphthenic hydrocarbons normallyencountered in straight-run gasolines are generally approximatelyequally divided between those having hexamethylene rings (hydroaromatichydrocarbons) and those having pentamethylene rings. The naphthenichydrocarbons having pentamethylene rings are unable to Withstand therequired relatively drastic treating conditions without extensivecracking. Also, they are prone'to be dehydrogenated to unsaturatedproducts such as cyclopentadiene, which undergo secondary reactions withthe formation of tarry substances which quickly coat the cata lystsurface and render the catalyst ineflective. It is for this reason thatit has frequently been suggested to selectively remove or destroy themajor part of the naphthenic hydrocarbons having pentamethylene ringsprior to any attempt to upgrade the gasoline by catalytic reforming.

The hydrocarbon ,oil may be a full range gasoline having an initialboiling point'within the range of about 10 C. to about 38 C. and a finalboiling point Within the range of about 160 C. to about 225 C. or it maybe a somewhat narrower range material sometimes referred to as naphthahaving, for example, an initial boiling point between about 50 C. andabout C. and a final boiling point between about C. and about 225 C.

Recently, it was discovered that through the use of a promoted platinumcatalyst gasolines having a high concentration of naphthenichydrocarbons can be more effectively upgraded, without recourse to priortreatment to remove or destroy naphthenic hydrocarbons havingpentamethylene rings. In this process, known as the Platforming Process,a platinum catalyst is used in which the platinum is supported upon analumina and promoted by a halogen, e. g., chlorine and fluorine. Whenusing this special catalyst the naphthenic hydrocarbons havingpentamethylene rings are largely converted to aromatic hydrocarbons bydehydroisomerization. If the possible and desired. 7

process is described in U. S. Patent Numbers" 2,479,l09;

' (C acking a ti ity) "The flehy cg n t ng prom e' n oxide o a ul or oneo th jd lh d t.

r meta ea, t anium, vana i a hmm bm, ma anese, Qnick'cI, oly denum,cobalt, ru henium, rh dium, opal- 7 process is carried out under as'uflicie ntly hightpartial pressure of hydrogen, dehydrogenation ofthe' pentaaromas methylene rings and consequent rapid deactivation ofthe catalyst can be substantially avoided.f Substantial cracking of thenaphthenes cq ltainingpentamethylene rings,

nevertheless, takesplace and the yields, although higher thanobtainableby the previously known process using non-platinum catalysts,are not as high asltheoretically 2,479,1'10;'2,478',916 and 2,573,149.

.The suggested platinum catalysts are extremely sensitime, there is nosatisfactory method for repeatedly regenerating them .to restore theirinitial activity; It would,

' material.

ladium, tungsten, iridium, platinum, and thorium. These V metals may beapplied per se, butare more generally applied in combination with aninert support or carrier It is essential, however, that the support orcarrier material is not acidic in character. Thus, such materials aspure alumina, pure silica, activated carbon,

magn sia. and h likemayb us d; b t Such materials as clays,.silicaeal'umina composites,si caagn The Platforming catalyst and 7 tiveto poisons; are very costly, and, up to the present therefore, be highlydesirable to have available a process which combines the good points ofthe Platforming process while avoiding its shortcomings.

out havingto sacrifice the advantages connected with the 9 use of thePlatforming catalyst. Experimentation has now shown that such a processis possible. Thus,,excellent reforming of highly naphthenic gasolinesmay be fobtained with the use of much less platinum or evenPwhileidispensing with platinum altogether.

It would be a ,gr'eat advantageii thequantity'ot platinum needed'couldbe reduced orthe'use of platinum entirely avoided with- In our copendingapplication, Serial Number 292,439,

filed June 9, 1952 (corresponding to Netherlands application Number161,954), we have described a process using a platinum catalyst which isparticularly designed and effective for the upgrading of gasoline andnaphthas which contain'only small concentrations of naphthenichydrocarbons, e. g., less than 30%; In'said process the upgrading of thegasoline is efiected in two steps, in the first of which an acidcracking catalyst containing a dehydrogenation promoter is employedand-in the second of which a dehydrogenation catalyst,fwhicl 1 is devoidof any acidity or cracking'act'ivity, is employed. In said process theloss in yield due to cracking of naphtheni'c hy oc on a insp n m hyl ncngs ur n he s stage of the treatment is 'notan important considerationsince the concentration of such 1 1apl 1then ic hydrocarbons in thereaction mixture is quitejlqwr When treating gasoline fractions whichare concentrated in naphthenic hydroearbons,i, je., have above30%inaphthenes,on'the otb r ha d. h lo s n y d h n t ea n ac o n tothe'method of saidcopendingapplication is relatively ighz 1 r In theprocessiof the present invention gasolinesihav- 'ing 'such' highconcentration of naphthenic hydrocarbons, including those havingpentamethylene rings, are upgraded with low loss'by a two stage processin which the catalyst and conditions in the first step are adjusted suchthat naphthenic hydrocarbons having pentamethylene rings aresubstantially unafiected while the naphthenic hydroc r ons a ing xamhylbn a s c l ebyd genated, 'In the second step ofthepr ocess'theeonditions and catalyst are chosen to completetthe upgradingvariation ofr th e process is dcseribedin"II/[.{S Patent;

l Number 2,550,531.

ata-

' of the gaso hrough ari us o herr c io saih l d n conversion of thenaphthenic posites, and various acid-treated carriers should not beused, 0 6, u ta le ca al con ists of pu s i a pregnated with 0.1 to 1%of platinum. V 'A platinum cata? lyst is recommended in the'first stagesince it has very strong dehydrogenation properties and therefore allowsa high rate ofltlirougjhput'tobe applied. On the other hand, anon-'platiniim-containing catalyst can also be applied. example of onesuch suitable catalyst is one which consists'of a combination of thesulfidestof V tungsten and nickel. This -catalyst sometimes exhibits anappreciable acidity'as freshly prepared, but this is lost after a shortperiod "of use. 'The tungsten sulfide nickel sulfide may be applied witha carrier such as alumina,

'but not with a carrier activated with acid, particularly withhydrofluoric 'acid. Carriers of the latter type cause undesired crackingwith loss of output under the treating conditions applied. When using acatalyst which does not contain platinum the catalyst may contain analkali such as potassium. The presence of the alkali prevents theexistence of any undesired acidity which may otherwise-be presentorbedeveloped inthe catalyst. i

Thereformingof .the gasoline is completed by treating the partiallyconverted product either with orrwithout intermediate separation ofhydrogen in a secondstep with a dehydrogenating catalyst which ispurposelypromoted by-an acid whereby naphthenic components hav ingpentamethylene rings are 'efliciently converted along with otherreforming reactions;

genation promoters, e.g., platinum. The essential difleronce is that thedehydrogenation promoter is used 'in combination with an acidicmaterial. Suitable acidic materials are silica-alumina, composites,silica-magnesia composites, acid-treated clays, acid-treated alumina.and other clay type cracking catalysts. The. preferred materials aresynthetic silica-alumina composites and alumina vvhibhhas been partiallyconverted to aluminum fluoride by treatment with hydrofluoric acid oranother suitablefluorinating agent, "The carrier material may; beacidified during the' catalyst preparation through the treatment-with'ahydrogen halide, e. g., hydrochloric acid, orthe acid nature of thecatalyst may be imparted during actual operation by' treatment in usewith a hydrogen halide or a substance producing'hydrogen halide underreaction conditions. Such materials are, for example,

benzene fluoride, ammonium fluoride, and tertiary butyl chloride. Y

The treating conditions, with the exception of the catalyst, canbe'substantia'lly the same in the two stages of thetreatment or they mayvary within permissible limits as follows: Temperature, 450500,C.;pressure, 30-100 0.5-5; hydrogen/hydrocarbon mole atmospheres; WHSVratio 3 10. i

The conversion of S-ring naphthenes into 6-ring naph-, themes andthedehydro'genation thereof to aromatics are equilibrium reactions. Byconverting the 6-ring naphthenespresent into aromatics in the firststage it is' achieved that in the second stage, when applying an aciddehydrogenation catalyst, the 5-ring naphthenesare converted'into 6-ringnaphthenes, which are dehydrogenated to aromatics underthereaction'conditions. These suc ;cessive treatments prevent considerablequantities of ,6-

ring naphthenes'from being lost, either directly'by'hy- WH SV weighthourly. space velocity, .which is the weight of the hydrocarb'onjfeedpassed overth weight of the catalyst inpne'bour. e

V V The dehydrogenation catalystused in the second stage may contain asits' essential ingredient one of the above-mentioned dehydro- Example Agasoline fraction with boiling point 113-19l C., O. N. F. 2=56,consisting of about 25% aromatic hydrocarbons, about 49% naphthenichydrocarbons and 26% paraffins, and obtained by distilling crudepetroleum, was hydroformed at a throughput rate of 2 kg. per litre ofcatalyst per hour together with 1000 litres of hydrogen per kg. ofinitial material, under a total pressure of 50 amt:

1. According to a one-stage method over 50 millilitres of a commercial100% nickel sulphide-tungsten sulphide catalyst with the followingresult:

Reaction temperature C 450 475 500 Yield "percent" 98 97 95 Percent byweight of aromatics 41 50 53 O. N. F-2 65 69 72 2. According to aone-stage method over 50 millilitres ofalumina-F-W-Ni=100:0.3:26.9:4.3-sulphidic catalyst, with the result:

Reaction tcmperatiu'e C" 450 475 500 Yield 05+ "percent" 90. 5 91 83Percent by weight of aromatics 35 39 46 O. N. F 72 76 3. According to atwo-stage method, in the first stage 50 millilitres of catalyst as usedaccording to (1) and in the second stage 50 millilitres of catalyst asapplied according to (2) being used, with the following result:

Reaction temperature C Yield 05 percent" The alumina-F-W-Ni-sulphidecatalyst was prepared as follows:

Aluminum hydroxide was precipitated at a pH of from 8 to 9 by mixing anapproximately 10% solution of AlCls-6H2O with an approximately 2.5%NHrOH solution. The precipitate obtained was filtered off and washedwith 0.5% ammonia until all the halogen had been removed, after which iswas re-washed with pure water.

A quantity of the precipitate, corresponding to 105 g. of dry substance,was treated with 15.6 g. of a 2.05% HF solution.

Subsequently 53.6 g. of (NI-L92 W84 was dissolved in 500 millilitres ofwater and 22 millilitres of 25 NH4OH saturated with H28 were added tothe solution. To this mixture 44.5 millilitres of a solution ofNi(NO3)2, containing 101.3 g. of Ni per litre of solution, were addeddrop by drop. Subsequently acidification was carried out with about 5 8millilitres of H2SO (25% by vol.) to a pH of 1.5.

The precipitate obtained was filtered oit and mixed with the aluminatreated with HF. The slurry was then 6 dried at 13 mm. of Hg whilenitrogen was passed through at 140 C.

The catalyst was tabletted to tablets of 5 by 3 mm. after 1% of graphitehad been added.

Vile claim as our invention:

' 1. Process for improving the anti-knock characteristics of naphthenicgasolines by catalytic treatment in the presence of hydrogen whichcomprises contacting the gasoline to be upgraded in the vapor phase inthe presence of hydrogen with a non-acidic dehydrogenation catalystselective for the dehydrogenation of naphthenic hydrocarbons havinghexamethylene rings at a temperature between 450" C. and 500 C. and apressure between 30 and atmospheres whereby naphthenic hydrocarbonshaving hexamethylene rings are dehydrogenated while the naphthenichydrocarbons having pentamethylene rings remain substantiallyunaffected, then contacting the resulting partially converted gasolinein the vapor phase and in the presence of hydrogen with a solid acidicdehydrogenation catalyst at a temperature between 450 C. and 500 C. anda pressure between 30 and 100 atmospheres, whereby naphthenichydrocarbons having pentamethylene rings are substantially converted.

2. Process for improving the anti-knock characteristics of naphthenicgasolines by catalytic treatment in the presence of hydrogen whichcomprises contacting the gasoline to be upgraded in the vapor phase andin the presence of hydrogen with a catalyst consisting of adehydrogenation promoter supported upon a carrier which is devoid ofacidity at a temperature between 450 C. and 500 C. and at a pressurebetween 30 and 100 atmospheres whereby naphthenic hydrocarbons havinghexamethylene rings are selectively dehydrogenated while the naphthenichydrocarbons having pentamethylene rings remain substantiallyunafiected, then contacting the .resulting partially converted gasolinein the vapor phase and in the presence of hydrogen with a catalystconsisting of a dehydrogenation promoter supported upon an acidiccracking catalyst at a temperature between 450 C.-and 500 C. and at apressure between 30 and 100 atmospheres whereby naphthenic hydrocarbonshaving pentamethylene rings are substantially converted.

3. Process for improving the anti-knock characteristics of naphthenicgasolines by catalytic treatment in the presence of hydrogen whichcomprises contacting the gasoline to be upgraded in the vapor phase andin the presence of hydrogen with a catalyst consisting of platinumsupported upon substantially pure silica at a temperature between 450 C.and 500 C. and at a pressure between 30 and 100 atmospheres wherebynaphthenic hydrocarbons having hexamethylene rings are selectivelydehydrogenated while the naphthenic hydrocarbons having pentamethylenerings remain substantially unafiected, then contacting the resultingpartially converted gasoline in the vapor phase and in the presence ofhydrogen with a catalyst consisting of a dehydrogenating metal promotersupported upon an alumina which has been treated with hydrofluoric acidat a temperature between 450 C. and 500 C. and at a pressure between 30and 100 atmospheres, whereby naphthenic hydrocarbons havingpentamethylene rings are substantially converted.

4. Process for improving the anti-knock characteristics of naphthenicgasolines by catalytic treatment in the presence of hydrogen whichcomprises contacting the gasoline to be upgraded in the vapor phase inthe presence of hydrogen with a catalyst consisting of sulfides oftungsten and nickel supported upon a non-acidic carrier containing analkali at a temperature between 450 C. and 500 C. and at a pressurebetween 30 and 100 atmospheres whereby naphthenic hydrocarbons havinghexamethylene rings are selectively dehydrogenated While the naphthenichydrocarbons having pentamethylene rings remain substantiallyunafiected, then contacting the resulting partially converted gasolinein the vapor phase and in the presence of hydrogen with a catalystconsisting of a de- '7 Refeences Cifedin the file of tfiis patent UNITEDSTATES PATENTS Kassel Oct. 30, 1951 Tun: I6, 19.53 g. Nov. '3', I953

1. PROCESS FOR IMPROVING THE ANTI-KNOCK CHARACTERISTICS OF NAPHTHENICGASOLINES BY CATALYSTIC TREATMENT IN THE PRESENCE OF HYDROGEN WHICHCOMPRISES CONTACTING THE GASOLINE TO BE UPGRADED IN THE VAPOR PHASE INTHE PRESENCE OF HYDROGEN, WITH A NON-ACIDIC DEHYDROGENATION CATALYSTSELECTIVE FOR THE DEHYDROGENATION OF NAPHTHENIC HYDROCARBONS HAVINGHEXAMETHYLENE RINGS AT A TEMPERATURE BETWEEN 450* C. AND 500* C. AND APRESSURE BETWEEN 30 AND 100 ATMOSPHERES WHEREBY NAPHTHENIC HYDROCARBONSHAVING HEXAMETHYLENE RINGS ARE DEHYDROGENATED WHILE THE NAPHTHENICHYDROCARBONS HAVING PENTAMETHYLENE RINGS REMAIN SUBSTANTIALLYUNAFFECTED, THEN CONTACTING THE RESULTING PARTIALLY CONVERTED GASOLINEIN THE VAPOR PHASE AND IN THE PRESENCE OF HYDROGEN WITH A SOLID ACIDICDEHYDROGENATION CATALYST AT A TEMPERATURE BETWEEN 450* C. AND 500* C.AND A PRESSURE BETWEEN 30 AND 100 ATMOSPHERES, WHEREBY NAPHTHENICHYDROCARBONS HAVING PENTAMETHYLENE RINGS ARE SUBSTANTIALLY CONVERTED.